FIG. 1 is an illustration of a drive rod-control rod assembly (CRA) connection 10 useable with example embodiment control drives. In most conventional PWR control rod assemblies, drive rod 11 and actuating rod 12 extend in lateral support tube 16 from above a reactor pressure vessel 1 down to a lockable spud or bayonet 13 that joins to CRA 15 via locking plug 14. CRA 15 contains neutron absorbent materials what can be used to control a nuclear chain reaction based on an amount of vertical insertion. Control rods are driven from above by vertical movement of actuating rod 12 and drive rod 13, under force from the control rod drive mechanism.
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